Charging Mobile Phones With Sound

Dr. Joe Briscoe and Dr. Steve Dunn from Queen Mary University of London (QMUL) are partnering with Microsoft to develop an energy-harvesting prototype (a nanogenerator) that could be used to charge a mobile phone using everyday background noise – such as traffic, music, and our own voices.

Zinc oxide possesses the property of generating voltage when it is been squashed or stretched. QMUL's researchers used it to form nanorods which respond to everyday sound, such as our voices, to produce electrical energy. The rods can be coated onto various surfaces in different locations making the energy harvesting quite versatile.

Using spray-on technique a thin layer of zinc oxide was formed on a plastic sheet. Mixed with other chemicals and heated to just 90°C, zinc oxide nanorods grew all over the surface of the sheet. Then cheap and cheerful aluminum foil, instead of expensive gold, was used as the electrical contacts. About the size of Nokia Lumia 925 the device was able to generate 5V, which is enough to charge a phone.

Dr Joe Briscoe commented: "Being able to keep mobile devices working for longer, or do away with batteries completely by tapping into the stray energy that is all around us is an exciting concept. This collaboration was an excellent opportunity to develop alternative device designs using cheap and scalable methods. We hope that we have brought this technology closer to viability."